In ordinary fracture treatment, when the fractured bone is displaced, the displacement is reduced, and then fixed to wait for natural repair and fusion of the bone. Example methods for fixing a bone include non-surgical external fixation using a splint or a cast, surgical internal fixation, and external skeletal fixation.
When surgery is required for treatment of a fractured bone, displacement of the bone is reduced and then the bone is fixed inside the body using, e.g., cables, pins, screws, plates and rods of metal.
Meanwhile, with the aging population, the problem of increase in number of elderly people who suffer fractured bones has arisen. It is known that decrease in activity level of elderly people due to fractures causes secondary problems due to the fractures such as muscle weakness and dementia or the like. Therefore, it is desirable to bring such elderly people back to their ordinary life as soon as possible.
However, since elderly people have brittle bones, when a bone of an elder person is fixed using a fastening tool such as a cable, the bone may be damaged if the fastening force is excessively strong. Also, if the fastening force is weak, fixation of a fractured part is insufficient, which may adversely affects the healing process.
Therefore, there is a demand for a wire having strength enough to provide sufficient fixation when a fractured bone part is fixed, as well as stretchability enough to absorb the excess of the fastening force where a fastening force is excessively strong, along with flexibility.
In order to solve the aforementioned problems, the present inventors have already developed linear members for medical use such as those disclosed in Patent Literatures 1 and 2.
The linear members for medical use in Patent Literatures 1 and 2 have a smooth outer shape compared to existing products. Therefore, the linear members can prevent a bone to be fixed and/or surrounding tissues from being damaged and thus are applicable to children's bones having low strength and elderly people's bones having insufficient bone mass and quality.
However, although the linear members for medical use in Patent Literatures 1 and 2 are excellent linear members for medical use in terms of stretchability and flexibility, the linear members may be insufficient in strength when it is necessary to fix a thick bone such as a thighbone or a hipbone with a strong fastening force.